Naturally occurring cerium (58Ce) is composed of 4 stable isotopes: 136Ce, 138Ce, 140Ce, and 142Ce, with 140Ce being the most abundant (88.45% natural abundance) and the only one that is theoretically stable. The others, 136Ce, 138Ce, and 142Ce are predicted to undergo double beta decay, which has never been observed. There are 35 radioisotopes that have been characterized, with the most stable being 144Ce, with a half-life of 284.89 days; 139Ce, with a half-life of 137.64 days and 141Ce, with a half-life of 32.505 days. All of the remaining radioactive isotopes have half-lives that are less than 4 days and the majority of these have half-lives that are less than 10 minutes.
The known isotopes of cerium range from 117Ce to 160Ce, in addition to 14 meta states.
List of isotopes
|-id=Cerium-117 | 117Ce | style="text-align:right" | 58 | style="text-align:right" | 59 | | style="text-align:center" | 2026
|-id=Cerium-118 | 118Ce | style="text-align:right" | 58 | style="text-align:right" | 60 | | style="text-align:center" | 2026
|-id=Cerium-119 | 119Ce | style="text-align:right" | 58 | style="text-align:right" | 61 | 118.95296(54)# | style="text-align:center" | 2025 | 200# ms[>310 ns]
| 5/2+#
|-id=Cerium-120 | 120Ce | style="text-align:right" | 58 | style="text-align:right" | 62 | 119.94661(54)# | style="text-align:center" | 2025 | 250# ms[>310 ns]
| 0+
|-id=Cerium-121 | rowspan=2|121Ce | rowspan=2 style="text-align:right" | 58 | rowspan=2 style="text-align:right" | 63 | rowspan=2|120.94344(43)# | rowspan=2 style="text-align:center" | 1997 | rowspan=2|1.1(1) s | β+ (99%) | 121La | rowspan=2|5/2(+#) | rowspan=2| | rowspan=2| |- | β+, p (1%) | 120Ba |-id=Cerium-122 | 122Ce | style="text-align:right" | 58 | style="text-align:right" | 64 | 121.93787(43)# | style="text-align:center" | 2005 | 2# s | β+ | 122La | 0+
|-id=Cerium-123 | rowspan=2|123Ce | rowspan=2 style="text-align:right" | 58 | rowspan=2 style="text-align:right" | 65 | rowspan=2|122.93528(32)# | rowspan=2 style="text-align:center" | 1984 | rowspan=2|3.8(2) s | β+ (?%) | 123La | rowspan=2|(5/2)(+#) | rowspan=2| | rowspan=2| |- | β+, p (?%) | 122Ba |-id=Cerium-124 | 124Ce | style="text-align:right" | 58 | style="text-align:right" | 66 | 123.93031(32)# | style="text-align:center" | 1978 | 9.1(12) s | β+ | 124La | 0+
|-id=Cerium-125 | rowspan=2|125Ce | rowspan=2 style="text-align:right" | 58 | rowspan=2 style="text-align:right" | 67 | rowspan=2|124.92844(21)# | rowspan=2 style="text-align:center" | 1978 | rowspan=2|9.7(3) s | β+ (?%) | 125La | rowspan=2|(7/2−) | rowspan=2| | rowspan=2| |- | β+, p (?%) | 124Ba |-id=Cerium-125m | style="text-indent:1em" | 125mCe | colspan="3" style="text-indent:2em" | 93.6(4) keV | style="text-align:center" | 2007 | 13(10) s | IT | 125Ce | (1/2+)
|-id=Cerium-126 | 126Ce | style="text-align:right" | 58 | style="text-align:right" | 68 | 125.923971(30) | style="text-align:center" | 1978 | 51.0(3) s | β+ | 126La | 0+
|-id=Cerium-127 | 127Ce | style="text-align:right" | 58 | style="text-align:right" | 69 | 126.922727(31) | style="text-align:center" | 1978 | 34(2) s | β+ | 127La | (1/2+)
|-id=Cerium-127m1 | style="text-indent:1em" | 127m1Ce | colspan="3" style="text-indent:2em" | 7.3(11) keV | style="text-align:center" | 1996 | 28.6(7) s | β+ | 127La | (5/2+)
|-id=Cerium-127m2 | style="text-indent:1em" | 127m2Ce | colspan="3" style="text-indent:2em" | 36.9(11) keV | style="text-align:center" | 1994 | >10 μs | IT | 127Ce | (7/2−)
|-id=Cerium-128 | 128Ce | style="text-align:right" | 58 | style="text-align:right" | 70 | 127.918911(30) | style="text-align:center" | 1968 | 3.93(2) min | β+ | 128La | 0+
|-id=Cerium-129 | 129Ce | style="text-align:right" | 58 | style="text-align:right" | 71 | 128.918102(30) | style="text-align:center" | 1977 | 3.5(3) min | β+ | 129La | (5/2+)
|-id=Cerium-130 | 130Ce | style="text-align:right" | 58 | style="text-align:right" | 72 | 129.914736(30) | style="text-align:center" | 1965 | 22.9(5) min | β+ | 130La | 0+
|-id=Cerium-130m | style="text-indent:1em" | 130mCe | colspan="3" style="text-indent:2em" | 2453.6(3) keV | style="text-align:center" | 1984 | 100(8) ns | IT | 130Ce | 7−
|-id=Cerium-131 | 131Ce | style="text-align:right" | 58 | style="text-align:right" | 73 | 130.914429(35) | style="text-align:center" | 1966 | 10.3(3) min | β+ | 131La | 7/2+
|-id=Cerium-131m | style="text-indent:1em" | 131mCe | colspan="3" style="text-indent:2em" | 63.09(9) keV | style="text-align:center" | 1966 | 5.4(4) min | β+ | 131La | (1/2+)
|-id=Cerium-132 | 132Ce | style="text-align:right" | 58 | style="text-align:right" | 74 | 131.911466(22) | style="text-align:center" | 1960 | 3.51(11) h | β+ | 132La | 0+
|-id=Cerium-132m | style="text-indent:1em" | 132mCe | colspan="3" style="text-indent:2em" | 2341.15(21) keV | style="text-align:center" | 1968 | 9.4(3) ms | IT | 132Ce | 8−
|-id=Cerium-133 | 133Ce | style="text-align:right" | 58 | style="text-align:right" | 75 | 132.911520(18) | style="text-align:center" | 1951 | 97(4) min | β+ | 133La | 1/2+
|-id=Cerium-133m | style="text-indent:1em" | 133mCe | colspan="3" style="text-indent:2em" | 37.2(7) keV | style="text-align:center" | 1967 | 5.1(3) h | β+ | 133La | 9/2−
|-id=Cerium-134 | 134Ce | style="text-align:right" | 58 | style="text-align:right" | 76 | 133.908928(22) | style="text-align:center" | 1951 | 3.16(4) d | EC | 134La | 0+
|-id=Cerium-134m | style="text-indent:1em" | 134mCe | colspan="3" style="text-indent:2em" | 3208.6(4) keV | style="text-align:center" | 1980 | 308(5) ns | IT | 134Ce | 10+
|-id=Cerium-135 | 135Ce | style="text-align:right" | 58 | style="text-align:right" | 77 | 134.909161(11) | style="text-align:center" | 1948 | 17.7(3) h | β+ | 135La | 1/2+
|-id=Cerium-135m | style="text-indent:1em" | 135mCe | colspan="3" style="text-indent:2em" | 445.81(21) keV | style="text-align:center" | 1970 | 20(1) s | IT | 135Ce | (11/2−)
|-id=Cerium-136 | 136Ce | style="text-align:right" | 58 | style="text-align:right" | 78 | 135.90712926(35) | style="text-align:center" | 1936 | colspan=3 align=center|Observationally stableTheorized to undergo β+β+ decay to 136Ba with a half-life over 3.2×1016 years | 0+ | 0.00186(2) | |-id=Cerium-136m | style="text-indent:1em" | 136mCe | colspan="3" style="text-indent:2em" | 3095.0(6) keV | style="text-align:center" | 1975 | 1.96(9) μs | IT | 136Ce | 10+
|-id=Cerium-137 | 137Ce | style="text-align:right" | 58 | style="text-align:right" | 79 | 136.90776242(39) | style="text-align:center" | 1948 | 9.0(3) h | β+ | 137La | 3/2+
|-id=Cerium-137m | rowspan=2 style="text-indent:1em" | 137mCe | rowspan=2 colspan="3" style="text-indent:2em" | 254.29(5) keV | rowspan=2 style="text-align:center" | 1955 | rowspan=2|34.4(3) h | IT (99.21%) | 137Ce | rowspan=2|11/2− | rowspan=2| | rowspan=2| |- | β+ (0.79%) | 137La |-id=Cerium-138 | 138Ce | style="text-align:right" | 58 | style="text-align:right" | 80 | 137.90599418(54) | style="text-align:center" | 1936 | colspan=3 align=center|Observationally stableTheorized to undergo β+β+ decay to 138Ba with a half-life over 4.4×1016 years | 0+ | 0.00251(2) | |-id=Cerium-138m | style="text-indent:1em" | 138mCe | colspan="3" style="text-indent:2em" | 2129.28(12) keV | style="text-align:center" | 1960 | 8.73(20) ms | IT | 138Ce | 7-
|-id=Cerium-139 | 139Ce | style="text-align:right" | 58 | style="text-align:right" | 81 | 138.9066470(22) | style="text-align:center" | 1948 | 137.642(20) d | EC | 139La | 3/2+
|-id=Cerium-139m | style="text-indent:1em" | 139mCe | colspan="3" style="text-indent:2em" | 754.24(8) keV | style="text-align:center" | 1956 | 57.58(32) s | IT | 139Ce | 11/2−
|-id=Cerium-140 | 140CeFission product | style="text-align:right" | 58 | style="text-align:right" | 82 | 139.9054484(14) | style="text-align:center" | 1924 | colspan=3 align=center|Stable | 0+ | 0.88449(51) | |-id=Cerium-140m | style="text-indent:1em" | 140mCe | colspan="3" style="text-indent:2em" | 2107.854(24) keV | style="text-align:center" | 1964 | 7.3(15) μs | IT | 140Ce | 6+
|-id=Cerium-141 | 141Ce | style="text-align:right" | 58 | style="text-align:right" | 83 | 140.9082860(14) | style="text-align:center" | 1951 | 32.505(10) d | β− | 141Pr | 7/2−
|-id=Cerium-142 | 142Ce | style="text-align:right" | 58 | style="text-align:right" | 84 | 141.9092502(26) | style="text-align:center" | 1924 | colspan=3 align=center|Observationally stable | 0+ | 0.11114(51) | |-id=Cerium-143 | 143Ce | style="text-align:right" | 58 | style="text-align:right" | 85 | 142.9123920(26) | style="text-align:center" | 1951 | 33.039(6) h | β− | 143Pr | 3/2−
|-id=Cerium-144 | 144Ce | style="text-align:right" | 58 | style="text-align:right" | 86 | 143.9136528(30) | style="text-align:center" | 1946 | 284.886(25) d | β− | 144Pr | 0+
|-id=Cerium-145 | 145Ce | style="text-align:right" | 58 | style="text-align:right" | 87 | 144.917265(36) | style="text-align:center" | 1954 | 3.01(6) min | β− | 145Pr | 5/2−#
|-id=Cerium-146 | 146Ce | style="text-align:right" | 58 | style="text-align:right" | 88 | 145.918812(16) | style="text-align:center" | 1953 | 13.49(16) min | β− | 146Pr | 0+
|-id=Cerium-147 | 147Ce | style="text-align:right" | 58 | style="text-align:right" | 89 | 146.9226899(92) | style="text-align:center" | 1964 | 56.4(10) s | β− | 147Pr | (5/2−)
|-id=Cerium-148 | 148Ce | style="text-align:right" | 58 | style="text-align:right" | 90 | 147.924424(12) | style="text-align:center" | 1964 | 56.8(3) s | β− | 148Pr | 0+
|-id=Cerium-149 | 149Ce | style="text-align:right" | 58 | style="text-align:right" | 91 | 148.928427(11) | style="text-align:center" | 1971 | 4.94(4) s | β− | 149Pr | 3/2−#
|-id=Cerium-150 | 150Ce | style="text-align:right" | 58 | style="text-align:right" | 92 | 149.930384(13) | style="text-align:center" | 1970 | 6.05(7) s | β− | 150Pr | 0+
|-id=Cerium-151 | 151Ce | style="text-align:right" | 58 | style="text-align:right" | 93 | 150.934272(19) | style="text-align:center" | 1997 | 1.76(6) s | β− | 151Pr | (3/2−)
|-id=Cerium-152 | 152Ce | style="text-align:right" | 58 | style="text-align:right" | 94 | 151.93668(22)# | style="text-align:center" | 1990 | 1.42(2) s | β− | 152Pr | 0+
|-id=Cerium-153 | 153Ce | style="text-align:right" | 58 | style="text-align:right" | 95 | 152.94105(22)# | style="text-align:center" | 1994 | 865(25) ms | β− | 153Pr | 3/2−#
|-id=Cerium-154 | 154Ce | style="text-align:right" | 58 | style="text-align:right" | 96 | 153.94394(22)# | style="text-align:center" | 1994 | 722(14) ms | β− | 154Pr | 0+
|-id=Cerium-155 | 155Ce | style="text-align:right" | 58 | style="text-align:right" | 97 | 154.94871(32)# | style="text-align:center" | 1994 | 313(7) ms | β− | 155Pr | 5/2−#
|-id=Cerium-156 | 156Ce | style="text-align:right" | 58 | style="text-align:right" | 98 | 155.95188(32)# | style="text-align:center" | 2017 | 233(9) ms | β− | 156Pr | 0+
|-id=Cerium-157 | 157Ce | style="text-align:right" | 58 | style="text-align:right" | 99 | 156.95713(43)# | style="text-align:center" | 2017 | 175(41) ms | β− | 157Pr | 7/2+#
|-id=Cerium-158 | 158Ce | style="text-align:right" | 58 | style="text-align:right" | 100 | 157.96077(43)# | style="text-align:center" | 2017 | 99(93) ms | β− | 158Pr | 0+
|-id=Cerium-159 | 159Ce | style="text-align:right" | 58 | style="text-align:right" | 101 | 158.96636(54)# | style="text-align:center" | 2026
| 1/2−#
|-id=Cerium-160 | 160Ce | style="text-align:right" | 58 | style="text-align:right" | 102 | | style="text-align:center" | 2026
| 0+
See also Daughter products other than cerium Isotopes of praseodymium Isotopes of lanthanum Isotopes of barium
References